There was also among the Romans a libra mensuralis, which the Greeks called λίτρα μετρικὴ, and distinguished from the λίτρα σταθμικὴ, or libra ponderalis. This consisted of 12 ounces, and was divided as the as. It was made commonly of horn, and divided by 12 lines, marking the ounces. This libra mensuralis weighed 10 ounces of oil, and of wine, 11 oz. 2 scr., 1 obolus, and 1 siliqua, according to the ponderal libra. The ancients all along supposed the weight of oil to be, to that of wine, as 9 to 10. This proportion of the specific gravity of these two liquors holds in this computation; for 11 oz., 2 scr. 1 ob. 1 sil., make 1600 siliquæ; and 10 ounces make 1440 siliquæ; and dividing both by 160, makes it as 9 to 10. According to this weight of wine assigned by Galen, the libra mensuralis contained 19·085 solid inches, somewhat less than ¾ of our pint, wine measure. But the Roman measures varying, in all appearance this originally was designed to contain 12 ponderal ounces of water, according to which weight it would be equal to 20·612 solid inches, the difference between the two being only 1·527 solid inches.
Roman Measures of Capacity for things dry. The modius was the third part of the amphora, or quadrantal, which was one half of the medimnus. The semimodius contained 8 sextarii. Sextarius and hemina are also measures of dry things, as so also quartarius, acetabulum, cyathus and concha.
Table of the Roman Measures of capacity for things Dry.
| English Corn Measure. | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pecks. | Gals. | Pints. | Sol. Inch. | |||||||
| Ligula | 0 | 0 | ¹⁄₄₈ | 0·01 | ||||||
| 4 | Cyathus | 0 | 0 | ¹⁄₁₂ | 0·04 | |||||
| 6 | 1½ | Acetabulum | 0 | 0 | ⅛ | 0·06 | ||||
| 24 | 6 | 4 | Hemina | 0 | 0 | ½ | 0·24 | |||
| 48 | 12 | 8 | 2 | Sextarius | 0 | 0 | 1 | 0·48 | ||
| 384 | 96 | 64 | 16 | 8 | Semimodius | 0 | 1 | 0 | 3·84 | |
| 768 | 192 | 128 | 32 | 16 | 2 | Modius | 1 | 0 | 0 | 7·68 |
Of the Arabian Measures. The knowledge of the Arabian measures is necessary for those who read the Arabian physicians, such as Avicenna, Rhases, Serapion, Mesue, and Haly Abbas.
Dorach, equal to the Roman amphora.
Aldorach, equal to 2 xestæ.
Johem, equal to the congius of the Romans.
Kist, equal to a Roman sextarius.